PURPOSE: To prepare the titled substance useful as a synthetic intermediate of pharmaceuticals, in high yield, by protecting the hydroxyl group of a specific compound, e.g. (1S, 2R, 3R, 5R)-2-carboxy-3-hydroxy-7,7-ethylenedioxy-bicyclo [3,3,0]octane, and reducing the protected compound.

CONSTITUTION: The compound of formula I (Z is protecting group of carbonyl group), e.g. (1S,2R,3R,5R)-2-carboxy-3-hydroxy-7,7-ethylenedioxy-bicyclo[3,3,0] octane, is made to react with excessive reagent for forming a protective group of the hydroxyl group in the presence of a solvent. The resultant compound of formula II (R1 is OH-protecting group; R2 is same as R1 or H) is made to react with a reducing agent such as lithium aluminum hydride in the presence of a solvent at about room temperature to obtain the compound of formula III which is useful as a synthetic intermediate of methanocycline derivative having strong blood platelet coagulation inhibiting action.